The most common procedure to obtain rock strength is the uniaxial compressive strength test (UCS). Extracting rock samples weakened by temperature can affect the estimation of the UCS values. Estimating UCS using the Point Load Test (PLT) is possible because both are linearly related. PLT needs smaller samples and is quicker and cheaper than the UCS test. This research determines UCS, Point Load Strength Index, and β-values (i.e., the ratio between UCS and Point Load Strength Index) of a limestone exposed to temperatures up to 900°C and then cooled on air or by immersion in water. Results show that strength and β-values decrease as temperature increases. There are two threshold temperatures in the relationship between point load strength and UCS in Pedra de Borriol samples: 600 °C for samples subjected to slow cooling and 400 °C for those subjected to quick cooling.
Most historical heritage worldwide was built using rocks, and reported incidents demonstrate that fires seriously damage or destroy them (e.g., Windsor Castle 1992, National Museum of Brazil 2018; Notre Dame Cathedral 2019, and Plasencia Church 2020). These events cause major economic costs, social alarm and important heritage losses. Studying fire incidents in historic stone buildings helps us understand how high temperatures affect these structures (Ioannou et al. 2017; Zhang et al. 2009). To rehabilitate and rebuild historical monuments affected by fire it is essential to know the effects of thermal damage on rocks as well as the effects of the cooling methods used to extinguish the fire.
During a fire, thermal stresses create micro-cracks in rocks, leading to a progressive decay in rock integrity (Jansen et al. 1993, David et al. 1999; Keshavarz et al. 2010). This damage can be caused by differential thermal expansion and/or thermal oxidation processes (Martínez-Ibáñez et al. 2020). Every type of rock reacts differently to temperature changes based on properties such as mineralogical composition, water absorption, porosity, and density. Furthermore, it is known that mechanical properties of rocks are directly related to their physical properties, then it is obvious the effect of temperature on the mechanical behaviour of rocks.
